Donald Trump's Republican critics are now pushing for a GOP-backed takedown

Republican presidential candidate Donald Trump speaks at a rally in Las Vegas on October 8, 2015. AP Photo/John Locher WASHINGTON (AP) — Don't expect Democrats to take down Donald Trump. If the GOP's baffled establishment wants to dismiss their party's billionaire presidential front-runner, it appears they'll have to do it themselves.

Quietly pleased the brash real estate mogul and reality TV star has become the face of the modern-day GOP, Democrats who specialize in opposition research are holding their fire. Some leading Republicans, meanwhile, have grown increasingly concerned by Trump's staying power, leading to fresh calls for an organized takedown campaign to protect the party's image heading into 2016.

"At some point, the things he says go from being 'crazy old Donald Trump' to defining — this is how Republicans think and feel. And that's dangerous," said Katie Packer, who served as 2012 Republican nominee Mitt Romney's deputy campaign manager.

Packer says there is "some rumbling" about a well-funded anti-Trump campaign and offered a wake-up call to Republicans who assume Trump's candidacy will ultimately collapse. "Folks have to remember that lead changes don't just happen," she said. "Something causes them to happen."

Trump represents exactly the kind of party standard-bearer Republican officials wanted to avoid after a disastrous 2012 election in which minority voters — Hispanics in particular — overwhelmingly abandoned the GOP.

The Republican National Committee concluded in a postelection study the party must adopt a more welcoming and inclusive tone on immigration. Yet Trump's candidacy is built upon his disdain for immigrants who are living in the country illegally, whom he has repeatedly referred to as dangerous criminals who must be deported en masse.

Democrats couldn't be happier.

They're collecting reams of negative information about Trump's business background. Leading groups such as the Democratic-allied research firm American Bridge have dispatched staff to New York, New Jersey and Delaware in recent weeks to examine Trump-related bankruptcy cases, Security and Exchange Commission filings and the many lawsuits to which the litigious Trump has been a part.

But they're not planning to release any of it anytime soon. They want Trump around as long as possible.

"The longer Donald Trump is high-fiving Jeb Bush and forcing (Sens.) John McCain and Rob Portman to say they'd back him in a general election, the more he's making clear the Republican Party's priorities, and how out of touch they are with American values and middle-class families," said American Bridge spokesman Ben Ray.

Instead of attacking Trump, the Democratic National Committee is trying to paint the rest of the GOP field with his brush. The party has released a series of Web videos casting Trump's positions as representative of his competitors, including one in which Trump is shown high-fiving Bush, the former Florida governor.

"Trump may be running for president, but his ideas are running the party," says one DNC video entitled the "Retrumplican Party."

Republican officials have been careful not to attack Trump publicly for fear he may leave the party and launch an independent candidacy — despite winning from him a pledge not to do so. But there was evidence of Republican concern during a recent private gathering of top donors to the Republican National Committee at Washington's Mayflower Hotel.

Republican pollster Frank Luntz, whom Trump has criticized personally, asked a group of roughly 100 donors to raise their hands to indicate support for various candidates. Just one person did so for Trump, which prompted moans across the room, according to two people inside who spoke on the condition of anonymity in order to discuss the private gathering.

Luntz then showed a series of video clips of Trump, including the reality television star's criticism of women and past support for Democrats. Many donors believed they were watching a rough cut of prospective anti-Trump ads, according to the people in the room.

"They were very engaged in the idea that somebody has to do something, or Donald Trump will destroy the party," said one of the people who attended the meeting of the donors and was in the room.

Luntz told The Associated Press that he regularly uses video clips during presentations and did not suggest to the gathering the material would be used against Trump.

"They may look at the video and say, 'Aha, there's something there,'" Luntz said of the donors, explaining that he intended only to highlight the key talking points of the 2016 election.

Meanwhile, as the Republican establishment crosses its fingers that Trump fails, the real estate mogul is attacking the party's other 2016 prospects one by one. Trump has engaged in a particularly aggressive war of words with Bush, once considered the party's front-runner.

Most of the campaigns of his rivals fear that any efforts to confront Trump directly could backfire and energize his anti-establishment supporters. Even Wisconsin Gov. Scott Walker didn't use Trump's name when exiting the race and calling on the party to rally against his potential ascendance to the GOP nomination.

Bush allies have gone further than most, with one recently describing Trump as a zombie candidate — suggesting that, with no realistic path to the presidency, he's already dead politically but doesn't know it.